/*
 * Copyright (c) 1999, 2011, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 *
 */

package javax.swing;

import java.awt.*;

import sun.awt.ModalExclude;
import sun.awt.SunToolkit;

/**
 * Popups are used to display a <code>Component</code> to the user, typically
 * on top of all the other <code>Component</code>s in a particular containment
 * hierarchy. <code>Popup</code>s have a very small life cycle. Once you
 * have obtained a <code>Popup</code>, and hidden it (invoked the
 * <code>hide</code> method), you should no longer
 * invoke any methods on it. This allows the <code>PopupFactory</code> to cache
 * <code>Popup</code>s for later use.
 * <p>
 * The general contract is that if you need to change the size of the
 * <code>Component</code>, or location of the <code>Popup</code>, you should
 * obtain a new <code>Popup</code>.
 * <p>
 * <code>Popup</code> does not descend from <code>Component</code>, rather
 * implementations of <code>Popup</code> are responsible for creating
 * and maintaining their own <code>Component</code>s to render the
 * requested <code>Component</code> to the user.
 * <p>
 * You typically do not explicitly create an instance of <code>Popup</code>,
 * instead obtain one from a <code>PopupFactory</code>.
 *
 * @see PopupFactory
 * @since 1.4
 */
public class Popup {

  /**
   * The Component representing the Popup.
   */
  private Component component;

  /**
   * Creates a <code>Popup</code> for the Component <code>owner</code>
   * containing the Component <code>contents</code>. <code>owner</code>
   * is used to determine which <code>Window</code> the new
   * <code>Popup</code> will parent the <code>Component</code> the
   * <code>Popup</code> creates to.
   * A null <code>owner</code> implies there is no valid parent.
   * <code>x</code> and
   * <code>y</code> specify the preferred initial location to place
   * the <code>Popup</code> at. Based on screen size, or other paramaters,
   * the <code>Popup</code> may not display at <code>x</code> and
   * <code>y</code>.
   *
   * @param owner Component mouse coordinates are relative to, may be null
   * @param contents Contents of the Popup
   * @param x Initial x screen coordinate
   * @param y Initial y screen coordinate
   * @throws IllegalArgumentException if contents is null
   */
  protected Popup(Component owner, Component contents, int x, int y) {
    this();
    if (contents == null) {
      throw new IllegalArgumentException("Contents must be non-null");
    }
    reset(owner, contents, x, y);
  }

  /**
   * Creates a <code>Popup</code>. This is provided for subclasses.
   */
  protected Popup() {
  }

  /**
   * Makes the <code>Popup</code> visible. If the <code>Popup</code> is
   * currently visible, this has no effect.
   */

  @SuppressWarnings("deprecation")
  public void show() {
    Component component = getComponent();

    if (component != null) {
      component.show();
    }
  }

  /**
   * Hides and disposes of the <code>Popup</code>. Once a <code>Popup</code>
   * has been disposed you should no longer invoke methods on it. A
   * <code>dispose</code>d <code>Popup</code> may be reclaimed and later used
   * based on the <code>PopupFactory</code>. As such, if you invoke methods
   * on a <code>disposed</code> <code>Popup</code>, indeterminate
   * behavior will result.
   */

  @SuppressWarnings("deprecation")
  public void hide() {
    Component component = getComponent();

    if (component instanceof JWindow) {
      component.hide();
      ((JWindow) component).getContentPane().removeAll();
    }
    dispose();
  }

  /**
   * Frees any resources the <code>Popup</code> may be holding onto.
   */
  void dispose() {
    Component component = getComponent();
    Window window = SwingUtilities.getWindowAncestor(component);

    if (component instanceof JWindow) {
      ((Window) component).dispose();
      component = null;
    }
    // If our parent is a DefaultFrame, we need to dispose it, too.
    if (window instanceof DefaultFrame) {
      window.dispose();
    }
  }

  /**
   * Resets the <code>Popup</code> to an initial state.
   */
  void reset(Component owner, Component contents, int ownerX, int ownerY) {
    if (getComponent() == null) {
      component = createComponent(owner);
    }

    Component c = getComponent();

    if (c instanceof JWindow) {
      JWindow component = (JWindow) getComponent();

      component.setLocation(ownerX, ownerY);
      component.getContentPane().add(contents, BorderLayout.CENTER);
      component.invalidate();
      component.validate();
      if (component.isVisible()) {
        // Do not call pack() if window is not visible to
        // avoid early native peer creation
        pack();
      }
    }
  }


  /**
   * Causes the <code>Popup</code> to be sized to fit the preferred size
   * of the <code>Component</code> it contains.
   */
  void pack() {
    Component component = getComponent();

    if (component instanceof Window) {
      ((Window) component).pack();
    }
  }

  /**
   * Returns the <code>Window</code> to use as the parent of the
   * <code>Window</code> created for the <code>Popup</code>. This creates
   * a new <code>DefaultFrame</code>, if necessary.
   */
  private Window getParentWindow(Component owner) {
    Window window = null;

    if (owner instanceof Window) {
      window = (Window) owner;
    } else if (owner != null) {
      window = SwingUtilities.getWindowAncestor(owner);
    }
    if (window == null) {
      window = new DefaultFrame();
    }
    return window;
  }

  /**
   * Creates the Component to use as the parent of the <code>Popup</code>.
   * The default implementation creates a <code>Window</code>, subclasses
   * should override.
   */
  Component createComponent(Component owner) {
    if (GraphicsEnvironment.isHeadless()) {
      // Generally not useful, bail.
      return null;
    }
    return new HeavyWeightWindow(getParentWindow(owner));
  }

  /**
   * Returns the <code>Component</code> returned from
   * <code>createComponent</code> that will hold the <code>Popup</code>.
   */
  Component getComponent() {
    return component;
  }


  /**
   * Component used to house window.
   */
  static class HeavyWeightWindow extends JWindow implements ModalExclude {

    HeavyWeightWindow(Window parent) {
      super(parent);
      setFocusableWindowState(false);
      setType(Window.Type.POPUP);

      // Popups are typically transient and most likely won't benefit
      // from true double buffering.  Turn it off here.
      getRootPane().setUseTrueDoubleBuffering(false);
      // Try to set "always-on-top" for the popup window.
      // Applets usually don't have sufficient permissions to do it.
      // In this case simply ignore the exception.
      try {
        setAlwaysOnTop(true);
      } catch (SecurityException se) {
        // setAlwaysOnTop is restricted,
        // the exception is ignored
      }
    }

    public void update(Graphics g) {
      paint(g);
    }

    public void show() {
      this.pack();
      if (getWidth() > 0 && getHeight() > 0) {
        super.show();
      }
    }
  }


  /**
   * Used if no valid Window ancestor of the supplied owner is found.
   * <p>
   * PopupFactory uses this as a way to know when the Popup shouldn't
   * be cached based on the Window.
   */
  static class DefaultFrame extends Frame {

  }
}
